<!-- HTML header for doxygen 1.8.6-->
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
<meta http-equiv="X-UA-Compatible" content="IE=9"/>
<meta name="generator" content="Doxygen 1.8.13"/>
<title>OpenCV: samples/cpp/tutorial_code/ImgTrans/Sobel_Demo.cpp</title>
<link href="../../opencv.ico" rel="shortcut icon" type="image/x-icon" />
<link href="../../tabs.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="../../jquery.js"></script>
<script type="text/javascript" src="../../dynsections.js"></script>
<script type="text/javascript" src="../../tutorial-utils.js"></script>
<link href="../../search/search.css" rel="stylesheet" type="text/css"/>
<script type="text/javascript" src="../../search/searchdata.js"></script>
<script type="text/javascript" src="../../search/search.js"></script>
<script type="text/x-mathjax-config">
  MathJax.Hub.Config({
    extensions: ["tex2jax.js", "TeX/AMSmath.js", "TeX/AMSsymbols.js"],
    jax: ["input/TeX","output/HTML-CSS"],
});
//<![CDATA[
MathJax.Hub.Config(
{
  TeX: {
      Macros: {
          matTT: [ "\\[ \\left|\\begin{array}{ccc} #1 & #2 & #3\\\\ #4 & #5 & #6\\\\ #7 & #8 & #9 \\end{array}\\right| \\]", 9],
          fork: ["\\left\\{ \\begin{array}{l l} #1 & \\mbox{#2}\\\\ #3 & \\mbox{#4}\\\\ \\end{array} \\right.", 4],
          forkthree: ["\\left\\{ \\begin{array}{l l} #1 & \\mbox{#2}\\\\ #3 & \\mbox{#4}\\\\ #5 & \\mbox{#6}\\\\ \\end{array} \\right.", 6],
          forkfour: ["\\left\\{ \\begin{array}{l l} #1 & \\mbox{#2}\\\\ #3 & \\mbox{#4}\\\\ #5 & \\mbox{#6}\\\\ #7 & \\mbox{#8}\\\\ \\end{array} \\right.", 8],
          vecthree: ["\\begin{bmatrix} #1\\\\ #2\\\\ #3 \\end{bmatrix}", 3],
          vecthreethree: ["\\begin{bmatrix} #1 & #2 & #3\\\\ #4 & #5 & #6\\\\ #7 & #8 & #9 \\end{bmatrix}", 9],
          cameramatrix: ["#1 = \\begin{bmatrix} f_x & 0 & c_x\\\\ 0 & f_y & c_y\\\\ 0 & 0 & 1 \\end{bmatrix}", 1],
          distcoeffs: ["(k_1, k_2, p_1, p_2[, k_3[, k_4, k_5, k_6 [, s_1, s_2, s_3, s_4[, \\tau_x, \\tau_y]]]]) \\text{ of 4, 5, 8, 12 or 14 elements}"],
          distcoeffsfisheye: ["(k_1, k_2, k_3, k_4)"],
          hdotsfor: ["\\dots", 1],
          mathbbm: ["\\mathbb{#1}", 1],
          bordermatrix: ["\\matrix{#1}", 1]
      }
  }
}
);
//]]>
</script><script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js"></script>
<link href="../../doxygen.css" rel="stylesheet" type="text/css" />
<link href="../../stylesheet.css" rel="stylesheet" type="text/css"/>
</head>
<body>
<div id="top"><!-- do not remove this div, it is closed by doxygen! -->
<div id="titlearea">
<!--#include virtual="/google-search.html"-->
<table cellspacing="0" cellpadding="0">
 <tbody>
 <tr style="height: 56px;">
  <td id="projectlogo"><img alt="Logo" src="../../opencv-logo-small.png"/></td>
  <td style="padding-left: 0.5em;">
   <div id="projectname">OpenCV
   &#160;<span id="projectnumber">4.5.2</span>
   </div>
   <div id="projectbrief">Open Source Computer Vision</div>
  </td>
 </tr>
 </tbody>
</table>
</div>
<!-- end header part -->
<!-- Generated by Doxygen 1.8.13 -->
<script type="text/javascript">
var searchBox = new SearchBox("searchBox", "../../search",false,'Search');
</script>
<script type="text/javascript" src="../../menudata.js"></script>
<script type="text/javascript" src="../../menu.js"></script>
<script type="text/javascript">
$(function() {
  initMenu('../../',true,false,'search.php','Search');
  $(document).ready(function() { init_search(); });
});
</script>
<div id="main-nav"></div>
</div><!-- top -->
<!-- window showing the filter options -->
<div id="MSearchSelectWindow"
     onmouseover="return searchBox.OnSearchSelectShow()"
     onmouseout="return searchBox.OnSearchSelectHide()"
     onkeydown="return searchBox.OnSearchSelectKey(event)">
</div>

<!-- iframe showing the search results (closed by default) -->
<div id="MSearchResultsWindow">
<iframe src="javascript:void(0)" frameborder="0" 
        name="MSearchResults" id="MSearchResults">
</iframe>
</div>

<div class="header">
  <div class="headertitle">
<div class="title">samples/cpp/tutorial_code/ImgTrans/Sobel_Demo.cpp</div>  </div>
</div><!--header-->
<div class="contents">
<p>Sample code using Sobel and/or Scharr OpenCV functions to make a simple Edge Detector </p><div class="image">
<img src="../../Sobel_Derivatives_Tutorial_Result.jpg" alt="Sobel_Derivatives_Tutorial_Result.jpg"/>
<div class="caption">
Sample screenshot</div></div>
<p>Check <a class="el" href="../../d2/d2c/tutorial_sobel_derivatives.html">the corresponding tutorial</a> for more details</p>
<div class="fragment"><div class="line"></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d1/d4f/imgproc_2include_2opencv2_2imgproc_8hpp.html">opencv2/imgproc.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d6/d87/imgcodecs_8hpp.html">opencv2/imgcodecs.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d4/dd5/highgui_8hpp.html">opencv2/highgui.hpp</a>&quot;</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include &lt;iostream&gt;</span></div><div class="line"></div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d2/d75/namespacecv.html">cv</a>;</div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d8/dcc/namespacestd.html">std</a>;</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main( <span class="keywordtype">int</span> argc, <span class="keywordtype">char</span>** argv )</div><div class="line">{</div><div class="line">  <a name="_a0"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html">cv::CommandLineParser</a> parser(argc, argv,</div><div class="line">                               <span class="stringliteral">&quot;{@input   |lena.jpg|input image}&quot;</span></div><div class="line">                               <span class="stringliteral">&quot;{ksize   k|1|ksize (hit &#39;K&#39; to increase its value at run time)}&quot;</span></div><div class="line">                               <span class="stringliteral">&quot;{scale   s|1|scale (hit &#39;S&#39; to increase its value at run time)}&quot;</span></div><div class="line">                               <span class="stringliteral">&quot;{delta   d|0|delta (hit &#39;D&#39; to increase its value at run time)}&quot;</span></div><div class="line">                               <span class="stringliteral">&quot;{help    h|false|show help message}&quot;</span>);</div><div class="line"></div><div class="line">  cout &lt;&lt; <span class="stringliteral">&quot;The sample uses Sobel or Scharr OpenCV functions for edge detection\n\n&quot;</span>;</div><div class="line">  parser.<a name="a1"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a84cda3794b765332bfe43bf8367222fb">printMessage</a>();</div><div class="line">  cout &lt;&lt; <span class="stringliteral">&quot;\nPress &#39;ESC&#39; to exit program.\nPress &#39;R&#39; to reset values ( ksize will be -1 equal to Scharr function )&quot;</span>;</div><div class="line"></div><div class="line">  <span class="comment">// First we declare the variables we are going to use</span></div><div class="line">  <a name="_a2"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> image,src, src_gray;</div><div class="line">  <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> grad;</div><div class="line">  <span class="keyword">const</span> <a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a> window_name = <span class="stringliteral">&quot;Sobel Demo - Simple Edge Detector&quot;</span>;</div><div class="line">  <span class="keywordtype">int</span> ksize = parser.<a name="a3"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a190215863579a6d244dccfd261ee0224">get</a>&lt;<span class="keywordtype">int</span>&gt;(<span class="stringliteral">&quot;ksize&quot;</span>);</div><div class="line">  <span class="keywordtype">int</span> <a name="a4"></a><a class="code" href="../../d6/d84/namespacecv_1_1quality_1_1quality__utils.html#ae55d1c89ff5761730174745401162743">scale</a> = parser.<a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a190215863579a6d244dccfd261ee0224">get</a>&lt;<span class="keywordtype">int</span>&gt;(<span class="stringliteral">&quot;scale&quot;</span>);</div><div class="line">  <span class="keywordtype">int</span> delta = parser.<a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a190215863579a6d244dccfd261ee0224">get</a>&lt;<span class="keywordtype">int</span>&gt;(<span class="stringliteral">&quot;delta&quot;</span>);</div><div class="line">  <span class="keywordtype">int</span> ddepth = <a name="a5"></a><a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga9d2ee1a8334733dea7482a47a88e0f87">CV_16S</a>;</div><div class="line"></div><div class="line">  <a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a> imageName = parser.<a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a190215863579a6d244dccfd261ee0224">get</a>&lt;<a class="code" href="../../dc/d84/group__core__basic.html#ga1f6634802eeadfd7245bc75cf3e216c2">String</a>&gt;(<span class="stringliteral">&quot;@input&quot;</span>);</div><div class="line">  <span class="comment">// As usual we load our source image (src)</span></div><div class="line">  image = <a name="a6"></a><a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>( <a name="a7"></a><a class="code" href="../../d6/dba/group__core__utils__samples.html#ga3a33b00033b46c698ff6340d95569c13">samples::findFile</a>( imageName ), <a name="a8"></a><a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80af660544735200cbe942eea09232eb822">IMREAD_COLOR</a> ); <span class="comment">// Load an image</span></div><div class="line"></div><div class="line">  <span class="comment">// Check if image is loaded fine</span></div><div class="line">  <span class="keywordflow">if</span>( image.empty() )</div><div class="line">  {</div><div class="line">    printf(<span class="stringliteral">&quot;Error opening image: %s\n&quot;</span>, imageName.c_str());</div><div class="line">    <span class="keywordflow">return</span> EXIT_FAILURE;</div><div class="line">  }</div><div class="line"></div><div class="line">  <span class="keywordflow">for</span> (;;)</div><div class="line">  {</div><div class="line">    <span class="comment">// Remove noise by blurring with a Gaussian filter ( kernel size = 3 )</span></div><div class="line">    <a name="a9"></a><a class="code" href="../../d4/d86/group__imgproc__filter.html#gaabe8c836e97159a9193fb0b11ac52cf1">GaussianBlur</a>(image, src, <a name="a10"></a><a class="code" href="../../dc/d84/group__core__basic.html#ga346f563897249351a34549137c8532a0">Size</a>(3, 3), 0, 0, <a name="a11"></a><a class="code" href="../../d2/de8/group__core__array.html#gga209f2f4869e304c82d07739337eae7c5afe14c13a4ea8b8e3b3ef399013dbae01">BORDER_DEFAULT</a>);</div><div class="line"></div><div class="line">    <span class="comment">// Convert the image to grayscale</span></div><div class="line">    <a name="a12"></a><a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#ga397ae87e1288a81d2363b61574eb8cab">cvtColor</a>(src, src_gray, <a name="a13"></a><a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#gga4e0972be5de079fed4e3a10e24ef5ef0a353a4b8db9040165db4dacb5bcefb6ea">COLOR_BGR2GRAY</a>);</div><div class="line"></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> grad_x, grad_y;</div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> abs_grad_x, abs_grad_y;</div><div class="line"></div><div class="line">    <a name="a14"></a><a class="code" href="../../d4/d86/group__imgproc__filter.html#gacea54f142e81b6758cb6f375ce782c8d">Sobel</a>(src_gray, grad_x, ddepth, 1, 0, ksize, scale, delta, <a class="code" href="../../d2/de8/group__core__array.html#gga209f2f4869e304c82d07739337eae7c5afe14c13a4ea8b8e3b3ef399013dbae01">BORDER_DEFAULT</a>);</div><div class="line"></div><div class="line">    <a class="code" href="../../d4/d86/group__imgproc__filter.html#gacea54f142e81b6758cb6f375ce782c8d">Sobel</a>(src_gray, grad_y, ddepth, 0, 1, ksize, scale, delta, <a class="code" href="../../d2/de8/group__core__array.html#gga209f2f4869e304c82d07739337eae7c5afe14c13a4ea8b8e3b3ef399013dbae01">BORDER_DEFAULT</a>);</div><div class="line"></div><div class="line">    <span class="comment">// converting back to CV_8U</span></div><div class="line">    <a name="a15"></a><a class="code" href="../../d2/de8/group__core__array.html#ga3460e9c9f37b563ab9dd550c4d8c4e7d">convertScaleAbs</a>(grad_x, abs_grad_x);</div><div class="line">    <a class="code" href="../../d2/de8/group__core__array.html#ga3460e9c9f37b563ab9dd550c4d8c4e7d">convertScaleAbs</a>(grad_y, abs_grad_y);</div><div class="line"></div><div class="line">    <a name="a16"></a><a class="code" href="../../d2/de8/group__core__array.html#gafafb2513349db3bcff51f54ee5592a19">addWeighted</a>(abs_grad_x, 0.5, abs_grad_y, 0.5, 0, grad);</div><div class="line"></div><div class="line">    <a name="a17"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>(window_name, grad);</div><div class="line">    <span class="keywordtype">char</span> key = (char)<a name="a18"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">waitKey</a>(0);</div><div class="line"></div><div class="line">    <span class="keywordflow">if</span>(key == 27)</div><div class="line">    {</div><div class="line">      <span class="keywordflow">return</span> EXIT_SUCCESS;</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="keywordflow">if</span> (key == <span class="charliteral">&#39;k&#39;</span> || key == <span class="charliteral">&#39;K&#39;</span>)</div><div class="line">    {</div><div class="line">      ksize = ksize &lt; 30 ? ksize+2 : -1;</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="keywordflow">if</span> (key == <span class="charliteral">&#39;s&#39;</span> || key == <span class="charliteral">&#39;S&#39;</span>)</div><div class="line">    {</div><div class="line">      scale++;</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="keywordflow">if</span> (key == <span class="charliteral">&#39;d&#39;</span> || key == <span class="charliteral">&#39;D&#39;</span>)</div><div class="line">    {</div><div class="line">      delta++;</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="keywordflow">if</span> (key == <span class="charliteral">&#39;r&#39;</span> || key == <span class="charliteral">&#39;R&#39;</span>)</div><div class="line">    {</div><div class="line">      scale =  1;</div><div class="line">      ksize = -1;</div><div class="line">      delta =  0;</div><div class="line">    }</div><div class="line">  }</div><div class="line">  <span class="keywordflow">return</span> EXIT_SUCCESS;</div><div class="line">}</div></div><!-- fragment --> </div><!-- contents -->
<!-- HTML footer for doxygen 1.8.6-->
<!-- start footer part -->
<hr class="footer"/><address class="footer"><small>
Generated on Fri Apr 2 2021 11:36:29 for OpenCV by &#160;<a href="http://www.doxygen.org/index.html">
<img class="footer" src="../../doxygen.png" alt="doxygen"/>
</a> 1.8.13
</small></address>
<script type="text/javascript">
//<![CDATA[
addTutorialsButtons();
//]]>
</script>
</body>
</html>
